Abstract: A method and system for performing direct memory access (DMA) transfers using operating system allocated I/O buffers provides a mechanism for device to device transfers without utilizing global system memory. Memory is allocated on a local bus to which both devices have a requested degree of affinity and transfers are performed to and from this memory. Operating system routines provide for selection of global system memory or local memory based on whether there is local memory available to which both devices have a requested degree of affinity. The memory can be deallocated after each transfer and reallocated for each subsequent transfer.

Abstract: A method and system for functional kernel verification testing within a data processing system is described. The method and system of the present invention performs imbedded functional verification test suites on selected kernel components within the data processing system when system administrator kernel component power-on self tests are required during an operating system boot operation. When an error is detected during the imbedded functional verification testing for a selected kernel component, it is reported based on the severity level. For a low or minor functional error, a warning is sent to the user and for a high or major functional error, the data processing system is immediately halted and a service call is generated. Additionally, to correct for the functional error, the data processing system may be enabled to de-install the most recent update of the kernel component.

Abstract: A data processing system and method are described for generating virtual memory descriptors which include pretranslated physical addresses. The data processing system has a virtual memory address space and a main memory. The main memory includes a first plurality of physical addresses. A temporary association is established between a region of the main memory and a segment of the virtual memory address space. The region of main memory is addressed utilizing a second plurality of physical addresses. The segment of virtual memory is addressed utilizing a plurality of virtual addresses. In response to the establishment of the temporary association, a virtual memory descriptor is generated and is utilized to address the segment. Each of the plurality of virtual addresses is translated to one of the second plurality of physical addresses. Each translated one of the second plurality of physical addresses is stored in the memory descriptor.

Abstract: A system, method and computer program are provided for maintaining time accurately and synchronously across a plurality of interconnected processors in a data processing system. Each processor has its own time base register and access to a single time delta variable. Time is reported as the sum of a processor's time base register and the time delta variable. Time base registers are set only at system initialization or boot; thereafter, any system wide time changes are effected by changing only the time delta variable value.

Abstract: A method of changing the functionality of a statically bound device driver, by dynamically extending the static device driver using a registered driver extension. The static device driver has a plurality of handlers or functions (such as input/output functions) used to control a device that is connected to or part of the computer system, and the driver extension modifies at least one of these functions, although it can be used to change several, or even all, of the functions. In the embodiment wherein the computer system is a UNIX-type workstation having a kernel residing in the memory, the static device driver is loaded in the kernel and is dynamically extended by providing at least one entry point for the driver extension.

Abstract: An exception handler for a computer system, particularly for performance monitoring facilities, employs implementation-dependent steps executed from a kernel extension which is more application level than kernel level. The implementation-independent kernel is involved only at very minimum level for a prologue to the exception handling routine. First a kernel extension registers an exception with the processor by storing the address of a pointer to a first-level interrupt handler; this address is stored in a location in kernel data storage, in non-paged memory. When an exception condition is reached, state is saved and the address location is checked to see if an exception has been registered. If so, the address is used to go to the first-level interrupt handler, which is at the kernel extension level. The first-level interrupt handler may access a second-level interrupt handler.

Abstract: A method of using a debugger for a computer operating system by providing a statically bound debugger driver which can be used early in the boot process, and further providing one or more dynamic debugger drivers which can be loaded after system initialization. The core portion of the operating system, such as the kernel for a UNIX-type workstation, makes a determination of whether any hardware device is connected to the computer that is of the type of debugger devices supported by the statically bound driver; if so, then the debugger can be used early in the boot process, but if not, provision is made for calling the dynamic debugger driver from some other portion of the operating system software, such as from the boot filesystem or PAL. The dynamic debugger driver may be selected from a plurality of dynamic debugger drivers, the particular selected dynamic debugger driver being associated with the particular hardware device that is actually connected to the computer.

Abstract: A method of providing a dynamic abstraction layer, such as a boot filesystem, for a computer having a particular hardware platform, in order to make a basic operating system more portable. The method includes storing the dynamic boot filesystem in a protected space in the computer before the normal boot sequence, and then retrieving the dynamic boot filesystem from the protected space during the boot sequence and loading the retrieved dynamic boot filesystem. The computer firmware first loads a simulated boot image which contains the dynamic boot filesystem, and then loads an operating system boot image which contains the operating system and instructions for retrieving the dynamic boot filesystem. A default boot filesystem may be used if no previously stored dynamic boot filesystem is found. In a UNIX embodiment, the dynamic boot filesystem includes a hardware-dependent PAL (Portable Assist Layer).

Abstract: An improved method of providing an operating system for a computer by defining an interface between the operating system and the computer's firmware. An executable file (soft ROS) is placed in a boot image so as to run, before execution of the real operating system, in response to the firmware seeking the operating system. The soft ROS includes instructions to determine whether the firmware conforms to the standardized interface. If so, then no special action is taken and control is passed to the operating system, but if the firmware is non-conforming in any manner, the soft ROS executes a firmware emulation module which provides the interface with the operating system. The firmware emulation module can provide missing dependencies of the firmware to the operating system, fix a defect in the firmware, or translate functions of the firmware to the pre-defined interface. This method isolates the operating system from firmware dependencies, making the operating system more portable.

Abstract: An improved operating system for a computer provides support for specific hardware components. The operating system is loaded by first loading a base portion which initializes the operating system and determines the particular type of hardware components present. Then, appropriate software components are loaded that are specifically associated with the hardware components. The hardware components can be detected by leaving a trace in the memory device that is associated with the software component and later retrieving the trace, or by testing the computer for the hardware component. The hardware component may be a bus architecture selected from a group of bus architectures, and bus-independent interfaces are defined which are mapped to addresses in the kernel. Alternatively, the software component can include a PAL which contains specific instructions for communicating with the hardware component. The PAL is constructed from a plurality of files each associated with the hardware component.

Abstract: An exception handler for a computer system, particularly for performance monitoring facilities, employs implementation-dependent steps executed from a kernel extension which is more application-level than kernel level. The implementation-independent kernel is involved only at very minimum level for a prologue to the exception handling routine. First, a kernel extension registers an exception with the processor by storing the address of a pointer to a first-level interrupt handler; this address is stored in a location in kernel data storage, in non-paged memory. When an exception condition is reached, state is saved and the address location is checked to see if an exception has been registered. If so, the address is used to go to the first-level interrupt handler, which is at the kernel extension level. The first-level interrupt handler may access a second-level interrupt handler.

Abstract: An exception handler for a computer system, particularly for performance monitoring facilities, employs implementation-dependent steps executed from a kernel extension which is more application-level than kernel level. The implementation-independent kernel is involved only at very minimum level for a prologue to the exception handling routine. First a kernel extension registers an exception with the processor by storing the address of a pointer to a first-level interrupt handler; this address is stored in a location in kernel data storage, in non-paged memory. When an exception condition is reached, state is saved and the address location is checked to see if an exception has been registered. If so, the address is used to go to the first-level interrupt handler, which is at the kernel extension level. The first-level interrupt handler may access a second-level interrupt handler.

Abstract: A method and apparatus for enabling AIX device driver (DD) created for a uniprocessor (UP) system to run unchanged on a symmetrical multiprocessor system (SMP). Device drivers are processed by a funnelling mechanism so that UP device drivers always runs on a "Master" processor in a multi-processor system. New device drivers written for the SMP system are permitted to bypass the funneling mechanism and proceed directly to execution on any available processor in the SMP system. Device registration services are provided which examine DD flags looking for a new unique flag indicating that the device driver is SMP enabled. If the flag is not present, then emulating a uniprocessor environment for execution of that device driver.